1. Field of the Invention
The present invention relates generally to an electrical connector, and more particularly to an improvement in an electrical connector used for putting connecting terminals provided on a circuit board, such as a flexible printed circuit board (FPC), conductors provided in a flexible flat cable assembly (FFC) or the like in electrical connection with another electrical device, such as a main solid circuit board.
2. Description of the Prior Art
In the field of electronic apparatus including various portable telephones, a relatively small-sized flexible printed circuit board or flexible flat cable assembly is often mounted on a main printed circuit board, on which various electrical parts are directly mounted, by means of an electrical connector which is fixed to and connected electrically with the main printed circuit board. The electrical connector has a plurality of conductive contacts for coming into contact with connecting terminals provided on the flexible printed circuit board or conductors in the flexible flat cable assembly and is operative to connect, through the conductive contacts, the connecting terminals provided with the flexible printed circuit board or the conductors in the flexible flat cable assembly with conducting circuit pattern portions formed on the main printed circuit board.
For example, a previously proposed electrical connector, which is used for mounting a flexible printed circuit board on a main printed circuit board, is provided with a housing made of insulator which has an opening through which the flexible printed circuit board is partially inserted into the housing. In the housing, a plurality of conductive contacts are arranged along the opening. These conductive contacts are operative to come into contact with a plurality of connecting terminals provided on the flexible printed circuit board when the flexible printed circuit board is partially inserted into the housing through the opening. The electrical connector is further provided with an actuator which is supported rotatably to the housing to be common to the conductive contacts arranged in the housing. When the actuator is rotated in regard to the housing, each of the conductive contacts is partially moved in the housing.
Each of the conductive contacts arranged in the housing is made of conductive resilient material to have a fixed part which is fixed to the housing and a movable part coupled with the fixed part. The fixed part of the contact is connected electrically with a conducting circuit pattern portion provided on the main printed circuit board. The movable part of the conductive contact constitutes an operating part which is moved by the actuator.
In the previously proposed electrical connector as mentioned above, when the flexible printed circuit board is partially inserted into the housing through the opening provided thereon and the actuator is rotated in a predetermined direction, the actuator operates to move the operating part of each of the conductive contacts to come into press-contact with a corresponding one of the connecting terminals provided on the flexible printed circuit board so that the flexible printed circuit board is held by the conductive contacts, as shown in, for example, the Japanese patent application published before examination under publication number 2002-270290 (Publication document 1). Then, when the actuator, by which the operating part of each of the conductive contacts is brought into press-contact with the corresponding connecting terminal provided on the flexible printed circuit board so that the flexible printed circuit board is held by the conductive contacts, is rotated in a direction opposite to the predetermined direction, the operating part of each of the conductive contacts is allowed by the actuator to move for getting out of press-contact with the corresponding connecting terminal provided on the flexible printed circuit board so that the flexible printed circuit board is loosened from holding by the conductive contacts.
In such an electrical connector as shown in the published document 1, each of the conductive contacts is formed into an H-shaped member. The H-shaped member has a pair of beams coupled with each other through a connecting portion. One of the beams constitutes the fixed part of the conductive contact and the other of the beams constitutes the operating part of the conductive contact. When the flexible printed circuit board is partially inserted into the housing through the opening provided thereon, a part of the flexible printed circuit board, on which the connecting terminals are provided, is put between the fixed and operating parts of each of the conductive contacts so that the flexible printed circuit board is temporary held by the conductive contacts.
Then, when the actuator is rotated for moving the operating part of each of the conductive contacts to come into press-contact with the corresponding connecting terminal on the flexible printed circuit board, the part of the flexible printed circuit board, on which the connecting terminals are provided, is held between the fixed part of each of the conductive contacts and the operating part of each of the conductive contacts which is brought into press-contact with the corresponding connecting terminal.
Further, there has been another type of the previously proposed electrical connector which is provided with a housing having an opening through which a flexible printed circuit board is partially inserted into the housing, a plurality of conductive contacts arranged along the opening on the housing and an actuator rotatable to the housing in almost the same manner as those of the electrical connector shown in the publication document 1, and in which the conductive contacts, each of which is formed into an H-shaped member having fixed and operating parts coupled with each other through a connecting portion, include first and second contacts different in shape from each other, as shown in, for example, the Japanese patent application published before examination under publication number HEI11-307198 (Publication document 2). In this type of electrical connector, each of the first contacts is shaped to have a relatively narrow space between the fixed and operating parts thereof and each of the second contacts is shaped to have a relatively broad space between the fixed and operating parts thereof. The operating part of each of the first contacts extends into the opening provided on the housing to reach more deeply than the operating part of each of the second contacts extending into the opening.
In the electrical connector as shown in the published document 2, when the flexible printed circuit board is partially inserted into the housing through the opening provided thereon and a part of the flexible printed circuit board, on which the connecting terminals are provided, is put between the fixed and operating parts of each of the first and second contacts, the flexible printed circuit board is temporarily held substantially by the first contacts, each of which is shaped to have the relatively narrow space between the fixed and operating parts thereof. That is, only each of the first contacts is operative to exert temporarily substantial holding force on the flexible printed circuit board inserted partially into the housing.
In the electrical connector thus proposed previously to be used for mounting the flexible printed circuit board on the main printed circuit board, when the flexible printed circuit board is partially inserted into the housing through the opening provided thereon, the part of the flexible printed circuit board inserted into the housing is put between the fixed and operating parts of each of the conductive contacts arranged in the housing and thereby the flexible printed circuit board is temporarily held by the conductive contacts. The conductive contacts thus holding temporarily the flexible printed circuit board is operative to exert temporary holding force on the flexible printed circuit board inserted partially into the housing.
An intensity of temporary holding force by each of the conductive contacts acting on the flexible printed circuit board in the previously proposed electrical connector is in inverse proportion to the space between the fixed and operating parts of each of the conductive contacts in the opening provided on the housing in a condition in which the actuator is inoperative. That is, the intensity of temporary holding force by each of the conductive contacts acting on the flexible printed circuit board is relatively small when each of the conductive contacts is formed to have a relatively broad space between the fixed and operating parts thereof and the intensity of temporary holding force by each of the conductive contacts acting on the flexible printed circuit board is relatively large when each of the conductive contacts is formed to have a relatively narrow space between the fixed and operating parts thereof. Then, after the conductive contacts have been once assembled into the housing, it is difficult to control the intensity of temporary holding force by each of the conductive contacts acting on the flexible printed circuit board.
It has been usual that the conductive contacts are desired to be sure in a certain extent in holding temporarily the flexible printed circuit board when the flexible printed circuit board is inserted partially into the housing and therefore it is likely to set each of the conductive contacts to exert a relatively large temporary holding force on the flexible printed circuit board inserted partially into the housing. However, in the electrical connector as shown in the published document 1, since the flexible printed circuit board is inserted partially into the housing against the temporary holding force by each of the conducting contacts acting on the flexible printed circuit board, a disadvantage that a relatively large thrusting force is required for inserting the flexible printed circuit board partially into the housing and therefore a thrusting operation for partial insertion of the flexible printed circuit board into the housing is deteriorated in operability is brought about when each of the conductive contacts is set to exert the relatively large temporary holding force on the flexible printed circuit board inserted partially into the housing. This disadvantage is especially severe when a large number of conductive contacts are provided in the housing.
Further, in the case of the electrical connector as shown in the published document 2, since only each of the first contacts, which is shaped to have the relatively narrow space between the fixed and operating parts thereof, is operative to exert substantially the temporary holding force on the flexible printed circuit board inserted partially into the housing, it is avoidable to set the temporary holding force acting on the flexible printed circuit board inserted partially into the housing to be relatively large. However, in the electrical connector as shown in the published document 2, the first contacts, each of which is shaped to have the relatively narrow space between the fixed and operating parts thereof, and the second contacts, each of which is shaped to have the relatively broad space between the fixed and operating parts thereof, are intermixed in the housing and therefore a disadvantage that an inspection and control with the aid of an image processing apparatus to the conductive contacts including the first and second contacts cannot be surely and effectively conducted, so that a quality control for keeping the electrical connector in quality at a predetermined level is inevitably complicated and lacking in reliability are brought about.